1. Technical Field
The present invention relates to an airbag apparatus including a case, an airbag folded and received in the case, and an airbag cover for covering the folded airbag.
2. Related Art
In an airbag apparatus described in Patent Document 1, an airbag cover arranged to cover a protruding opening of a box-shaped case with a folded airbag received therein has four side walls. The four side walls extend from a peripheral edge of a door portion, which covers the protruding opening, and are arranged on an outer peripheral side of a peripheral wall portion of the case. Two of four the side walls opposing to each other as attaching wall portions are attached to the peripheral wall portion of the case.
In an airbag apparatus described in Patent Document 2, an upper side wall of side walls of an airbag cover is arranged on an inner peripheral side of a peripheral wall portion of a case.    Patent Document 1: JP-A-2013-071567    Patent Document 2: JP-A-2007-008471
In the airbag apparatus described in Patent Document 1, there is no member intended to cover an inner peripheral side of the peripheral wall portion of the case, and therefore, a inflating airbag is likely to come in contact with vicinities of corner portions of a peripheral edge of the protruding opening of the case. In the airbag apparatus described in Patent Document 2, a part of the inner peripheral side of the peripheral wall portion of the case is covered with the side wall of the airbag cover. However, the side wall is attached to the case by being fastened together with an inflator, thereby causing an operation of mounting the airbag cover to the case to be difficult.